1. Field of the Invention
The present invention relates to an arrangement for measuring the planarity of a rolled strip which is under tension in a hot strip rolling train with a roughing train and a finishing train including several roll stands and a reel. In addition, the present invention relates to measuring rolls which are used in such an arrangement.
2. Description of the Related Art
Planarity deviations of rolled strips are caused by length differences over the width of the strip. Since the strip is under tension, length differences are at least partially compensated by elastic elongation. Accordingly, a direct measurement of the length differences is not possible. However, for determining the planarity errors, it is possible to utilize the tensile stress distribution which is dependent on the length differences.
In cold-rolled strips, for example, guide rollers are used for determining planarity deviations. The tension-proportional deflection force during the deflection of the strip is utilized as the measurement value.
DE 37 21 746 A1 discloses a method and a device for measuring the planarity of a rolled strip which is under tension in wide strip hot rolling trains. The tension distribution in the rolled strip is measured in segmented tension measuring rollers and the planarity of the strip is determined indirectly in this manner. However, in such segmented rollers, there is the great danger that the gaps of these rollers which are used and operate in aggressive media become clogged, so that the operation is significantly impaired.